1. Field of the Invention
This invention relates to wheelchairs, related devices, and methods for use, particularly for transportation.
2. Description of Related Art
The wheelchair is a common means of daily mobility for individuals with partial or complete impairment of sensory and motor function. As an alternative to walking, running, standing, kneeling, or crouching to move about in the physical environment or to enact change thereto, the wheelchair itself serves as a suitable, although limited, mobility means.
For many people, the wheelchair serves as an essential conveyance and for performing common activities that would otherwise be difficult, if not impossible, such as moving about in one's home, going shopping at the store, attending public gatherings, tending to a garden, and playing at the park with one's own children or grandchildren. For some, such activities may be performed independently, while for others considerable assistance may be necessary; the wheelchair is thus useful in both the context of independent mobility and in that of assistive transportation of a person with a disability. Whereas the wheelchair has traditionally been viewed as an object of confinement, advances in wheelchair technology, improved accessibility standards, and increasingly open-minded attitudes regarding the topic of disability have elevated the wheelchair as a tool for health, personal enjoyment and freedom.
Individuals who utilize wheelchairs for their daily mobility typically do so under the direction of physicians, licensed physical therapists, and other clinicians who are well-versed in the practice of compensating for physical disabilities through the use of adaptive mobility devices. Ideally, clinicians also educate and encourage their patients to engage in physical activity, to the greatest extent that their abilities will allow, for the sake of their overall well-being. Such physical activity helps to maintain cardiovascular health, muscle strength and endurance, flexibility, and range of motion. Additionally, ideal clinical practices emphasize the independence and safety of the individual, looking at his or her day-to-day activities in the home, in the neighborhood, and in the surrounding community.
Manually-propelled wheelchairs, from a holistic health standpoint, are preferred over motorized wheelchairs, the latter which, in many cases, contributes to a downward spiral of deconditioning during which the user's cardiovascular health, muscle strength and endurance, flexibility and range of motion all decline and thus reduce the user's overall health and independence. Manually-propelled wheelchairs require an occupant to exert his or her own upper body strength to transfer muscle-derived force to at least one of two rear drive wheels of the wheelchair to impart movement of the wheelchair in a desired direction of travel. In the process, the user experiences the benefits of physical exercise and maintains the aforementioned aspects of an active and healthy lifestyle.
Manually-propelled wheelchairs, nevertheless, possess limitations with regard to their suitability for the broad and heterogeneous range of physical environments which people regularly encounter as they alternate between indoor and outdoor spaces, or as they come upon a ground surface with a different texture as compared with that previously being traversed. Different kinds of surfaces, whether they be carpet or hard-wood flooring, concrete streets, sidewalks, gravel or dirt pathways, grassy fields, or sandy beaches, for example, all impose different challenges requiring different levels of strength and different kinds of maneuvering. The marked disparity between a flat, smooth parking lot and a trail layered with sand, gravel, and loose woodchips (all which might be encountered during the same visit to a local, state, or federal park) presents a physically demanding situation which may discourage some wheelchair users and their families from fully enjoying such public resources or which may put the individual at risk for injury due to the significant exertion, strain, and imbalance he or she may experience.
Common to manually-propelled wheelchairs is at least one forward pivotable caster assembly comprising a smaller diameter wheel which, as a result of having a wheel rotational axis disposed rearward relative to a vertical pivot axis of the caster assembly, causes the entire caster assembly to passively assume an orientation of forward travel while the wheelchair is motivated in the forward direction. As the wheelchair is motivated in other directions, such as to the side or in reverse, the forward pivotable caster assembly will passively pivot and the caster wheel will passively rotate such that the wheelchair may be freely maneuvered in all directions of travel. The freedom with which the caster assembly pivots and the wheel rotates is why pivotable casters are ubiquitous in wheelchair design, and the correct functioning of a caster assembly depends on factors such as the geometry and size of the caster assembly, the diameter and width of the caster wheel, and the traction of the caster wheel as it rolls over the ground surface.
Further, the utility of the caster assembly depends largely on the extent to which it bears the weight of the front end of the wheelchair and how successfully it carries this weight smoothly over the ground surface. In situations during which the caster sinks into the ground surface, such as on sand, snow, or gravel, the caster may be rendered useless and may even prove to be dangerous. Generally, the larger and wider the caster wheel, the better the weight distribution and the more readily it will roll over the ground surface. As most manually-propelled wheelchairs comprise a pair of forward pivotable caster assemblies, if they are not optimally suited to the terrain, such a pair can be even more problematic at times when one caster wheel is engaged with the ground surface and the other is not, in that the overall wheelbase of the wheelchair while traversing a rough or uneven surface is compromised and the user may lose balance and fall out of the wheelchair.
On the other hand, if a wheelchair is fitted with very large caster wheels, the maneuverability of the wheelchair will suffer when the user is faced with negotiating tight spaces requiring sharp turns, such as in kitchens, bedrooms, bathrooms, elevators, and office spaces. Thus, a forward pivotable caster assembly having a more petite structure, comprising a smaller caster wheel, and disposed closer to the rear wheels, longitudinally speaking, will prove to be best adapted for indoor use; this stands in stark contrast with the optimum caster arrangement for outdoor use which favors a larger robust caster assembly comprising a larger caster wheel and disposed on the wheelchair in a way that, instead, maximizes the longitudinal wheelbase for greater forward stability.
The contrast between indoor floor surfaces and outdoor terrain may vary depending on seasonal factors such as rain and snowfall, which significantly impact traction; this may be further influenced by the frequency of efforts, or lack thereof, to maintain and clear roadways, sidewalks, and driveways. For example, urban residences may benefit from prompt snow removal and de-icing services, whether by public services or by private homeowners' associations, whereas rural neighborhoods or farmsteads, for example, may not have access to such services. A wheelchair user residing rurally may thus experience a more profound contrast between the indoor environment and that of the outdoors.
Transit in urban environments as well as long-distance travel, which may involve transportation in vehicles such as cars, buses, trains, airplanes, watercraft, or larger vessels, require the wheelchair user to adapt to the space allowed inside the vehicle upon boarding and to again adapt to the space outside the vehicle upon arriving at his or her destination. In some situations, such as in the case of a wheelchair user traveling by car, the user may be required to exit or “transfer” out of the wheelchair and into a driver's or passenger's seat, and may be further required to disassemble the wheelchair in order to stow the separable components inside the vehicle. Similar situations may be encountered in the case of a wheelchair user requiring the assistance of a friend, family member, or other attendant, in that the user may need to be lifted out of the wheelchair and into the vehicle and the wheelchair subsequently stowed in a separate area of the vehicle. In other situations, a wheelchair user may desire to board a bus or train and situate herself amongst other passengers. Rather than struggle to maneuver around in the limited space with a large all-terrain caster assembly, and risk bumping into others or posing a trip hazard therefor, it would be preferable for the wheelchair user to quickly detach the adaptive caster assembly or temporarily stow it in an alternate position until the user exits the vehicle and again wishes to utilize it for negotiating rough terrain.
The aforementioned considerations are central to prior and ongoing efforts to develop adaptive devices, which enable a wheelchair user, clinician, caretaker, assistant, or medical staff member to suitably adapt, modify, or convert a wheelchair according to the demands of the physical environment being encountered.
Improved wheelchair adapter designs and methods have been devised which may address one or more of these aforementioned weaknesses or other weaknesses in the prior art. Such weaknesses, however, are mentioned here only for illustrative background purposes. The embodiments hereafter described, while typically addressing one or more weaknesses in the prior art, need not directly or indirectly address all or any of the aforementioned weaknesses in the prior art to be within the scope of the various embodiments hereafter claimed. Further, any advantages stated or apparently inherent to any of the embodiments described hereafter are not intended as limitations that must necessarily be found in any or all aspects of the invention.